Process for making fuming nitric acid

Abstract

A process for making fuming nitric acid involving the reacting of nitrogen dioxide gas with dry hydrogen chloride gas to produce the fuming nitric acid directly, and to produce as a co-product nitrosyl chloride gas; separating the formed liquid fuming nitric acid from the reaction gases and co-product gas; and stripping the liquid product and demisting the gaseous product to complete their separation.

We claim: 
     
       1. A gas-phase reaction process for making fuming nitric acid exclusively from dry gaseous NO 2  and dry gaseous HCl consisting of the steps of: (a) reacting said dry nitrogen dioxide gas with said dry hydrogen chloride gas to directly produce liquid droplets of fuming nitric acid and nitrosyl chloride gas;   (b) collecting the droplets of fuming nitric acid as a liquid and stripping the liquid to remove nitrosyl chloride and other trace gases dissolved therein;   (c) collecting the nitrosyl chloride gas and any stripped trace gases and demisting them to recover entrained fuming nitric acid therefrom; and   (d) recovering the liquid fuming nitric acid produced by said process.   
     
     
       2. The process as set forth in claim 1, wherein the stripping of the liquid includes the bubbling of dry nitrogen gas through the luquid and the subsequent mixing of the nitrogen gas and entrained trace gases with the nitrosyl chloride gas collected for demisting. 
     
     
       3. The process as set forth in claim 2, wherein the mixed and collected gases after demisting are cooled to liquify the nitrosyl chloride gas contained therein and for separation thereof in liquid phase. 
     
     
       4. The process as set forth in claim 3, wherein the nitrogen gas remaining after liquifaction of the nitrosyl chloride gas is recycled into the stripper.